Low yellowing scorch inhibitor composition

ABSTRACT

A scorch inhibitor composition for use an additive in the manufacture of polyurethane foams is based on a derivatized phenol, 4-tertbutyl catechol, and optionally, phenothiazine. The derivatized phenol is a di-tert-butyl phenol, preferably a 2,6 tert-butyl phenol substituted at least at the 4-position with an aliphatic, aromatic or aliphatic-aromatic moiety, of C 2  or greater. Preferably, the phenol is a liquid, and is chosen from among 2,6 di-tert-butyl-4-isobutyl phenol; 2,6 di-tert-butyl-4-nonyl phenol; and benzenepropanoic acid, 3,5-bis (1,1-dimethyl-ethyl)-4-hydroxy-.C7-C9 branched alkyl esters. The phenol may optionally possess combinations of heteroatoms, such as O, N, P or S, and may be dimerized.

BACKGROUND OF DESCRIPTION OF THE PRIOR ART

The product of the invention relates to scorch inhibitors added to thepolyol during or after its manufacture. Also the scorch inhibitor may beadded during the production of polyurethane foams. It is a known problemin the art that existing scorch inhibitors based on conventionalamine/phenolic blends cause foam to yellow following exposure to lightor NOx fumes. In general, yellowing has been attributed to a variety ofsources. For example, reaction products from additives like BHT lead tocolor bodies such as quinones (K. C. Smeltz, Textile Chemist anColorist, April 1983, Vol. 15, NO 4), and the polyurethane itself formscolor bodies such as diquinone imide as a result of photooxidation(Muller, Plastic Additives, 2nd edition, pg 119). Yellowing also comesfrom amine substances that presumably oxidize and form color bodies(Muller). It is believed that yellowing may be attributed to aminediscoloration.

U.S. Pat. No. 4,058,493 to Pokai et al teaches a foam composition, inwhich an inhibitor is added. Such additive may be a phenol substitutedwith tertiary-butyl groups, such as 2,6-di-tert-butyl-4-methylphenol(Ionol®[BHT]); (or) tert-butyl-catechol; (or) phenothiazine; amongothers. While such additives may act to inhibit scorch, they may alsocontribute to foam yellowing when exposed to NOx fumes, ultravioletradiation or fluorescent light. Importantly, when Ionol (BHT) is used,alone or in blends, excessive yellowing is observed under theseconditions, which is undesirable in many consumer applications (e.g.mattress foam).

Therefore, it is the object of the invention to provide an additive topolyurethane foams which inhibits scorch, but which also only minimallycontributes to discoloration arising from NOx, ultraviolet radiation andfluorescent light exposure.

SUMMARY

The inventors have surprisingly found that an additive based on acombination of a derivatized phenolic, 4-tertbutyl catechol (TBC) and,optionally, phenothiazine (PTZ), is effective against discolorationbased on the above factors.

A wide of range of phenolics have been found to be effective, in placeof BHT, in combination with the above components. Essentially, it hasbeen found that by substituting at the 4 position of a di-tert-butylphenolic with a moiety other than methyl (as in BHT), an improved resultis obtained. In particular, a 2,6-tert-butyl phenol, substituted at the4 position with an aromatic, aliphatic or aromatic-aliphatic moiety ofC₂ or greater, optionally possessing combinations of heteroatoms,preferably N, O, S or P. Optionally, those phenolics possessingcombinations of heteroatoms may be dimerized. It is also expected that a2,4-tert-butyl phenol substituted at the 4 position would also showbeneficial effects.

Among these are solid phenolics, such as Anox® 70 (2,2′-thiodiethylenebis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]) (formula I), Lowinox®TBM6 (4,4′-thio-bis-(2-t-butyl-5-methyl-phenol) and Lowinox® MD24(1,2-bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamoyl) hydrazine) (formulaIII); all from Great Lakes Chemical Corporation. It is also found thatLowinox® AH25 (2,5-di-t-amyl-hydroquinone) (formula II) offers improvedresults.

More preferred are liquid phenolics, such as Isonox® 132, Isonox® 232,both available from Schenectady Chemicals, Inc. and Irganox® 1135(Benzenepropanoic acid, 3,5-bis (1,1-dimethyl-ethyl)-4-hydroxy-.C7-C9branched alkyl esters—CAS Number: 125643-61-0) available from CibaSpecialty Chemicals.

Irganox® 1135 is benzenepropanoic acid, 3,5-bis(1,1-dimethyl-ethyl)-4-hydroxy-.C7-C9 branched alkly esters (FormulaIV):

Particularly preferred is Isonox® 232 (2,6 di-tert-butyl-4-nonyl phenol)(Formula V)

Most preferred is Isonox® 132 (2,6 di-tert-butyl-4-isobutyl phenol)(Formula VI)

Thus, the invention resides in a composition to be added to a polyol,during or after the manufacture thereof. Also, the composition may beadded during the manufacture of polyurethane foams. Such polyols andfoams are manufactured according to well-known methods, such as thoseset forth in U.S. Pat. No. 5,219,892 to Suhoza.

The basic formulation of the foam used during the testing phase is asfollows. Other known foam formulations can be used as well:

TABLE I parts Polyol 100.00 Distilled Water 5.50 L5770 Silicone (OSi)1.20 A127 Amine Catalyst (OSi) 0.47 Fyrol FR2 (Akzo/Nobel) 7.00 Dabco T9(Air Products) 0.25 Mondur TD8O Grade A TDI (Bayer AG) 70.80 Additive0.50

The scorch inhibitor (“Additive” in Table I) is a three-component systemcomprising:

(1) A derivatized phenol, from about 45-95 weight %, preferably 65-75weight %, more preferably about 66.5%

(2) 4-tert-butyl catechol, from about 5-55 weight %, preferably 22-35weight %, more preferably about 33%, and

(3) PTZ from 0 to 2 weight %, preferably 0 to 0.75%, more preferablyabout 0.5% Note: All weights % are weight % based on the total weight ofthe three-component system.

The scorch inhibitor may be present in the foam formulation based on arange of about 0.25 to 0.75 parts per 100 parts polyol, preferably about0.30 to 0.60, and more preferably about 0.35 to 0.50.

A comparative experiment was conducted comparing a composition based onIsonox 132 (from Schenectady International, Inc.) against BHT, on anequal weight basis in a tert-butyl catechol/PTZ blend. The tert-butylcatechol/PTZ amount remained the same in both the inventive (1) andcomparison (2) compositions. Both compositions 1 and 2 were added to thefoam formulation in the amount of the ‘additive’ of Table I. As shownbelow, it was discovered that replacing the methyl at the 4 position onthe phenol component (in this case with a tert-butyl group) stronglyinhibits color development in foam.

The Inventive Composition 1 (PLX 976)

Isonox 132 (2,6 ditert butyl 4 isobutyl phenol) 66.5%,

4-tertbutyl Catechol (33%)

and PTZ (app 0.5%)

We compared this composition to

The Comparative Composition 2

2,6-di-tert-butyl-4-methylphenol (BHT) (66.5%),

4-Tert butyl Catechol (33%)

and PTZ (app 0.5%).

In short, we substituted Isonox 132 for BHT. One would expect theperformance to be about the same with respect to scorch reduction, andindeed we did not see a noticeable difference on this parameter.However, scorch reduction is not the only concern in polyurethane foamproduction. Certain industries and uses require that the foam alsoresist yellowing, which is a common effect. Such yellowing over time maybe caused by several different factors, among them exposure to NO_(x)gases, exposure to ultraviolet radiation, and exposure to fluorescentlight. The foams produced based on additive Composition 1 andComparative Composition 2 were subjected to NO_(x) gases in a gas fadechamber, U.V. irradiation in a U.V. Weather-ometer, and to fluorescentlight.

We exposed the foams in a gas fade chamber, which generates NO, fumes.We then measured, using a colorimeter, the development of color overtime. A large value on this scale (b scale) indicates more intenseyellowing.

TABLE IIA Gas Fade Chamber Results (b Scale Colorimeter) TimeComparative (in hours) Composition 1 Composition 2 Δ b 3 5.42 4.12 −1.36 9.05 9.66 0.61 9.5 12.28 14.63 2.35 12 12.84 15.74 2.90

The results show that the foam containing comparative Composition 2develops a more intense yellow color, as indicated by the larger bvalue, than inventive composition A after extended exposure in the gasfade chamber. The difference between the two values (Δb) also steadilyincreases showing greater rate in color body production in composition 2vs. composition 1.

The colorimeter can also measure the extent of green developed in thesample. A positive number on this scale (a scale) indicates ‘redness’while a negative number indicates ‘greenness.’

TABLE IIB Gas Fade Chamber Results (‘a’ Scale Colorimeter) Time (inhours) Composition 1 Comparative Composition 2 3 −0.12 −0.09 6 −1.13−4.63 9.5 −1.18 −2.43 12 −0.92 −2.09

The result show that the foam containing Comparative Composition 2develops a more intense green color than Composition 1 (about double)after extended exposure in the Gas fade chamber.

Green and yellow when blended form a very intense yellow. This is quiteimportant to customers in the industry (e.g. manufacture of foam formattresses). In short, we found that Comparative Composition 2 developsa more intense yellow hue over time compared to Composition 1.

Thus, by exchanging BHT (which contains a primary carbon or methyl groupat the 4 postition on the 2,6 ditertbutyl phenol) with Isonox 132 (whichcontains a tertiary carbon at the 4 position) we have significantlyreduced yellow color development in foam when subjected to NO_(x) gassesgenerated in the Gas fade chamber.

We also examined the performance of each composition under fluorescentlight. B scale value, indicatin ‘yellowness’, are shown below:

TABLE IIIA Fluorescent Light Results (‘b’ Scale Colorimeter) Time (indays) Composition 1 Comparative Composition 2 12 7.14 9.46

‘a’ scale values are shown below (negative values show greenish hueswhile positive values show reddish hues);

TABLE IIIB Fluorescent Light Results (‘a’ scale Colorimeter) Time (indays) Composition 1 Comparative Composition 2 12 0.06 −0.17

Taking the values together we found that composition 2 darkened the foamtowards a deep yellow after 12 day exposure. Inventive composition 2comparatively darkened less. It is important to note that theapproximately 2.5 unit difference between the yellowness values is quitesignificant visually. One can clearly see less color deflection with thefoam using the inventive composition.

The same trends were observed when foam samples were exposed to U.V.light (carbon arc source) over time.

TABLE IV U.V. Weather-ometer Results (b Scale Colorimeter) TimeComparative (in hours) Composition 1 Composition 2 Δ b 1 1.81 1.70 −0.112 3.63 3.85 0.22 3 5.57 5.94 0.37 4 6.29 7.03 0.74 5 6.85 8.59 1.74 68.52 9.81 1.29 7 9.24 10.98 1.74 8 10.36 12.38 2.02 9 10.77 13.02 2.2510  11.36 13.67 2.31

The delta b values show that composition 2 is developing color bodiesmore rapidly than the inventive composition.

SCORCH STUDY TBC ALONE

As background, TBC was tested against a conventional or state of the artblend consisting of 4000 ppm BHT (a phenolic derivative) and 1000 ppmNaugard 445 (an alkylated diphenyl amine) in a foam formulation. Theextent of scorch was approximately equal for each of the test foams witha slight color difference in the scorched area of the foam core.

Foam swatches exposed to NOx fumes, however, showed a considerabledifference after many hours of exposure (Table V).

The TBC stabilized foam discolored less (developed less yellow color)after 9 hours exposure to NOx fumes compared to the conventional(BHT/alkylated diphenyl amine) blend.

TABLE V 6 Hrs NO_(x) 9 Hrs NO_(x) Scorch Fume Fume TBC alone LightYellow 8.00 11.2 Golden 10.00 16 Conventional BHT/Amine

TABLE VI COMPARING ISONOX ® 232 AND ISONOX ® 132 Conven- Conven- tionalBHT tional 945 PLX 976/232 PLX 976/132 6 Hrs Fume 5.67 8.80 6.31 6.26 9Hrs Fume 11.97 14.67 9.19 8.90

These liquid phenolic compounds were blended with tert butyl catecholfor the purpose of making a liquid scorch inhibitor package.‘Conventional 945’ refers to Vanox® 945 from R. T. Vanderbilt Company,Inc. Currently, liquid scorch inhibitors are highly desirable in theindustry. We found that Isonox 232 and Isonox 132 (Schenectady ChemicalsInc., N.Y.) worked equally well as TBC diluents (PLX 976/232 and PLX976/132) (Table VI). We also discovered that each of the two packagesstained foam much less than both commercially available (phenolic/amine)blends, conventional BHT and conventional 945.

Another liquid phenolic was examined in combination with tert-butylcatechol and PTZ. Irganox 1135 (available from Ciba-Giegy) adequatelydissolved TBC and phenothiazine to make a liquid scorch inhibitor.Again, we observed similar scorch protection with this package againstthe conventional 945 product (amine/phenolic blend) and the preferredinventive package PLX 976.

TABLE VIa FLUORESCENT LIGHT EXPOSURE 1135 Replacing ISONOX 132 inConventional 945 PLX 976 PLX 976 Unexposed b −1.68 −1.47 −1.47 6 Days b11.53 6.04 6.17 13 Days b 13.90 10.08 10.49

When exposed to fluorescent light the “1135” modified product performedsimilarly to PLX 976 but both developed less color (less yellowness)than the conventional product after 13 days (Table VI a). On this basis,Irganox 1135 is an acceptable alternative to Isonox 132 as an activediluent.

TABLE VIb WEATHEROMETER 1135 Replacing ISONOX 132 in Conventional 945PLX 976 PLX 976 Unexposed B −1.50 −1.30 1.58 3 Hours B 11.09 6.19 5.53 6Hours B 13.30 8.75 8.21 9 Hours B 14.82 11.29 11.42

When exposed to ultraviolet the foam containing Irganox 1135 performedsimilarly to PLX 976 but, as with fluorescent light exposure, bothdeveloped less color (less yellowness) than the conventional productafter extended exposure (Table VI b). Again, on this basis, Irganox 1135is an acceptable alternative to Isonox 132 as an active diluent for thecomposition.

TABLE VIc ATMOSPHERIC FUME CHAMBER 1135 Replacing ISONOX 132 in VANOX945 PLX 976 PLX 976 0 Hours (b) −1.78 −1.61 −1.69 4 Hours (b) 7.56 5.736.97 8 Hours (b) 13.43 8.53 12.36

When exposed to NO_(x) the foam containing Irganox 1135 performed poorlydeveloped more color (more yellowness) than PLX 976, almost identicalwith the conventional package (Table Vic). Though the 1135 modifiedpackage showed equal performance with PLX 976, in two of the threeevaluations, 1135 stains foam more intensely, than Isonox 132.

TABLE VII TBC/132 VS TBC/132/PTZ NOx Fume Fluorescent light U.V. light 3Hrs 6 Hrs 10 Days 22 Days 1 Hr 2.5 Hrs PTZ 7.64 9.67 7.15 11.51 2.46 4.97.67 9.87 7.09 11.27 2.43 5.06 No PTZ Conventional 9.52 13.72 11.9215.96 5.45 9.76 BHT Conventional 12.16 14.95 12.38 14.66 6.02 9.22 945

The TBC/Isonox® 132 scorch inhibitor package reduced scorch as well asthe conventional BHT/alkylated diphenyl amine blend and conventional 945but improvement in scorch performance was discovered by the addition ofphenothiazine. Each trial foam was then exposed to NOx fumes,fluorescent light and U.V. light (Table VII). Studies indicate that theaddition of phenothiazine did not adversely affect color stability (i.e.b values were approximately the same for TBC/Isonox 132 blend andTBC/Isonox 132/PTZ blend). Stated another way each foam (+PTZ and noPTZ) sample developed an equal yellow hue visually and quantitativelybut addition of PTZ improved scorch performance.

TABLE VIII EXAMINATION OF PLX-976 FORMULA NOx Fume Florescent Light U.V.Light 6 18 24 6 20 35 1 5 11 Hrs Hrs Hrs Days Days Days Hr Hrs Hrs PLX-4.39 10.76 12.5 4.73 10.18 13.04 1.7 7.12 12.9 976 BHT/ 3.36 11.24 13.44.64 13.44 15.28 1.42 7.02 13.54 976 232/ 7.4 14.29 15.8 4.87 10.6913.39 1.78 7.48 13.2 976 1010/ 5.13 13.78 15.66 4.6 10.80 14.14 1.567.89 13.95 976

We examined other phenolic compounds in combination with tert butylcatechol and phenothiazine (TBC/BHT/PTZ, TBC/J-232/PTZ, TBC/Irganox1010/PTZ). Each performed equally, in our scorch test, to the preferredexperimental blend PLX 976 (TBC/I-1 32/Phenothiazine) but swatchesexposed to the NOx Fumes, Fluorescent light and U.V. light showednoticeable differences (Table IV). Each test showed that after extendedexposure to stressful environments PLX 976 performed better. It isimportant to emphasize that the BHT and 1010 blends are solidcompositions, which although functional, are less preferred.

TABLE IX UNSTABILIZED VS PLX-976 Fume Fluorescent Chamber Light W-O-M7.0 Hrs 11.5 Hrs. 3 Days ½ Hr 1½ Hr Unstabilized 5.44 8.01 5.63 0.935.34 PLX-976 6.58 9.54 4.87 1.70 5.71 Conv. Blend 4.93 10.53 7.84 1.837.12 VANOX 945 10.21 14.60 10.40 5.68 10.49

While the preferred blend was shown to stain foam less in the tests sofar discussed we wanted to compare color development of this testcomposition and the two conventional blends against an unstabilized foamcomposition (typical foam recipe without a scorch inhibitor package).Our objective was to understand how much additional color is contributedfrom our novel package and the conventional offerings. We discoveredthat PLX 976 and the conventional blends (BHT and 945) impart color tofoam or stain the foam under all test conditions while the unstabilizedfoam composition, developed less color, except for fluorescent lightexposure, than all of the foam compositions containing an inhibitorpackage (Table V). However, PLX 976 added the least amount of color tothe foam among the scorch inhibitor packages studied. Importantly, theunstabilized foam composition showed severe scorching in our box foammicrowave test. Thus, any of the scorch inhibitors are preferred to noinhibitor package but among those studied PLX 976 is most preferredbecause it contributes the least amount of color.

TABLE X PARTIAL STEP STUDY AFC Fluorescent Light W-O-M 2 Hr 4 Hr 1 Day 9Days 2 Hr 4 Hr PLX-976 3.38 6.83 1.66 11.6 1.16 2.89 (5000 ppm) PLX-9763.05 6.49 1.18 11.0 0.86 2.59 (3500 ppm)

The use level of PLX 976 can be adjusted depending upon desired foamproduction rates and polyol manufacturers preferences. Examination oftwo different use levels showed that lower concentrations of PLX 976imparted less staining to foam swatches exposed to NOx fumes,fluorescent light or U.V. light.

TABLE XI FLUORESCENT LIGHT EXPOSURE C2 C31 C32 C33 C34 Conven- C3 ANOXLowinox Lowinox Lowinox tional PLX 70 in AH25 in TBM6 in MD24 in 945 976976 976 976 976 Un- exposed b −1.69 −1.56 −1.49 −1.28 −1.01 −1.31 2 Daysb 8.63 2.65 3.19 4.10 4.37 4.41 7 Days b 12.82 7.89 8.28 9.90 9.42 10.70

We examined other commercially available Phenolic derivatives and foundsimilar scorch performance with these packages vs. PLX 976. None of theblends shown (Table VII) were liquid of course with the exception of PLX976. In all cases after 7 days fluorescent light exposure, the proposedblends developed less color than the conventional package. However, PLX976 developed less color than the proposed blends throughout theexposure period.

TABLE XII WEATHEROMETER C2 C31 C32 C33 C34 Conven- C3 ANOX LowinoxLowinox Lowinox tional PLX 70 in AH25 in TBM6 in MD24 in 945 976 976 976976 976 Un- exposed b −1.53 −1.27 −1.32 −1.04 −1.10 −1.23 3 Hours b10.60 5.37 5.47 7.11 6.03 7.48 7 Hours b 13.57 9.25 9.70 11.35 9.9112.29

Table VIII shows similarities among several of the experimental blends(C3, C31, C33). The next group found to be significantly more yellowed(C32, C34). Both sets outperformed the control composition, conventional945 (Amine/Phenol blend).

TABLE XIII ATMOSPHERIC FUME CHAMBER C2 C31 C32 C33 C34 Conven- C3 ANOXLowinox Lowinox Lowinox tional PLX 70 in AH25 in TBM6 in MD24 in 945 976976 976 976 976 Un- exposed b −1.62 −1.60 −1.57 −1.24 −1.19 −1.52 3½Hours b 12.78 7.78 9.69 7.36 8.96 8.99 5 Hours b 14.79 8.80 11.49 8.009.80 10.00 11 Hours b 18.43 11.09 14.78 10.16 11.78 12.45

Table XIII shows the results of foam samples to 11 hours exposure in theatmospheric fume chamber. In all cases the new formulations outperformedthe conventional blend significantly.

In summary, it has been shown that tert-butyl catechol (TBC) can be aneffective scorch inhibitor. However, liquids are preferred in theindustry because of ease of handling. Accordingly, several commerciallyavailable liquid phenolics (Isonox 132, Isonox 232 and Irganox 1135) areshown to be effective diluents for TBC, with Isonox 132 imparting theleast color to foam according to stress tests, and therefore being themost preferred. Other effective phenolics, though solids and thereforenot diluents of TBC, include Lowinox AH25, Lowinox TBM6, Lowinox MD24,and Anox 70 (available from Great Lakes Chemical Corporation). Thus, thecombination of a derivatized phenolic and TBC, with or without PTZ, isshown to be a far superior additive than one based on BHT. It is clearthat by substituting at the 4 position or 2 position of the phenol witha moiety other than methyl, surprisingly improved results are achieved.Specifically, the invention encompasses a 2,6-tert-butyl phenol,substituted at the 4 position with an aromatic, aliphatic oraromatic-aliphatic moiety of C₂ or greater, optionally possessingcombinations of heteroatoms, preferably N, O, S or P. Optionally, thosephenolics possessing combinations of heteroatoms may be dimerized. PTZimproves scorch performance of the binary blend (TBC/Isonox 132) whilenot contributing to color deflection. All scorch inhibitors in thisstudy contribute to color when compared to unstabilized foam, but allscorch inhibitors reduce scorch while the unstabilized foam scorchedsignificantly.

The phenolic part of the formulation can be a blended composite ofphenolic derivatives (ie. Isonox 132 and Isonox 232 or Isonox 132 andAnox 70, etc). Ranges may be appropriately adjusted to achieve solutionstability.

With respect to TBC in the claimed composition, it is recommended thatit be present in the preferred range of about 25 to 35%, as there islittle difference in scorch within this range. Above 35%, the TBC beginsto crystallize out, though it may be dissolved again by heating. Below25%, it is believed that the composition will not be effective.

Quantitative Treatment of Data

The L,a,b values, from the Hunter L,a,b scale, measured using aTechnidyne Corp. Brightimeter Micro S4-M, quantifies color developed ina sample. The L,a,b scale, assigns to each variable (lightness (L), a,b) a corresponding dimension (x, y, z) and creates a color space. L,a,breadings taken from a specimen, represent color deviation from a whiteplaque standard. In practice, L,a,b readings are first acquired from acontrol then compared to L,a,b readings taken from a subject specimen.For our purposes, “b”values are compared against control values toquantitatively assess the “yellowness” of a subject specimen. However,though “b” values are convenient for our purposes a more fulldescription of “color drift” is delta E:

(L.a.b.), represents values taken from an arbitrary standard or control,while (L.a.b.)₂ represents values specific to a selected specimen. Thecomposite value ΔE, quantitatively expresses color drift away from thecontrol. (One might also recognize that ΔE is the distance formula for3-space. Thus the distance of any two points in 3-space is measuredusing this formula.) Importantly, the ΔE value is merely an absolutedistance from the control. In and of itself it does not say whether thedifference is “good” or “bad.” If the control had an undesirable color alarge AE is desirable because large values indicate a difference betweenthe control and specimen. A small ΔE would suggest that the specimenresembles the control, which in this case is undesirable. Conversely, ifthe control exhibits a desirable appearance a small ΔE is desirable. Wefound that ΔE calculations were equivalent in value to simple “b” valuesfrom the L.a.b. scale and chose to use the later in our evaluations.Also, the “b” value is fairly descriptive in that we can quickly assessthe “yellowness” of a given sample recognizing that yellowness increasesas b increases.

Qualitative Assessment of Scorch

Every formulation presented in this patent was subjected to a microwavescorch test. The resultant foam bun was allowed to cool after reactionand split open for visual inspection. We compared each formulation to acontrol (containing a conventional scorch inhibitor) run the same day.Since every formulation presented in this study performed similarly inscorch to conventional scorch inhibitor packages, we will onlyincidentally mention those results and rather focus on foam stress testsincluding NOx treatment, U.V. and fluorescent light exposure. It is ourposition that the uniqueness of the inventive formulation describedbelow arises from its low staining properties while providing scorchprotection equal to commercially available conventional packages.

What is claimed is:
 1. A scorch inhibitor composition for use anadditive in the manufacture of polyurethane foams, comprising: aderivatized di-tert-butyl phenol, substituted with an aromatic,aliphatic or aromatic-aliphatic moiety of C₂ or greater, the moietyoptionally possessing combinations of heteroatoms, which optionally maybe dimerized, 4-tertbutyl catechol, and optionally, phenothiazine. 2.The composition of claims 1, wherein the heteroatoms are one or morechosen from the group consisting of N, O, S and P.
 3. The composition ofclaim 1, wherein the phenol is chosen from the group consisting of2,2′-thiodiethylene bis[3-(3,5-di-t-butyl-4-hydroxyphenyl) propionate;4,4′-thio-bis-(2-t-butyl-5-methyl-phenol; and1,2-bis(3,5-di-tert-butyl-4-hydroxyhydrocinnamoyl) hydrazine.
 4. Thecomposition of claim 1, wherein the phenol is2,5-di-t-amyl-hydroquinone.
 5. The composition of claim 1, wherein thephenol is a 2,6-di-tert-butyl phenol derivative or a 2,4-di-tert-butylphenol derivative.
 6. The composition of claim 5, wherein the phenol is2,6 di-tert-butyl-4-isobutyl phenol.
 7. The composition of claim 5,wherein the phenol is 2,6 di-tert-butyl-4-nonyl phenol.
 8. Thecomposition of claim 5, wherein the phenol is a liquid phenol.
 9. Thecomposition of claim 8, wherein the phenol is chosen from the groupconsisting of 2,6 di-tert-butyl-4-isobutyl phenol; 2,6di-tert-butyl-4-nonyl phenol; and benzenepropanoic acid, 3,5-bis(1,1-dimethyl-ethyl)-4-hydroxy-.C7-C9 branched alkyl esters.
 10. Thecomposition of claim 9, comprising the following in weight percent:derivatized phenol at 45-95% tert-butyl-catechol at 5-55% phenothiazineat 0-2%.
 11. The composition of claim 10, comprising the following inweight percent: derivatized phenol at 65-75% tert-butyl-catechol at22-35% phenothiazine at 0-0.75%.
 12. The composition of claim 11,comprising the following in weight percent: derivatized phenol at about66.5% tert-butyl-catechol at about 33% phenothiazine at about 0.5%. 13.The composition of claim 5, comprising the following in weight percent:derivatized phenol at 45-95% tert-butyl-catechol at 5-55% phenothiazineat 0-2%.
 14. The composition of claim 13, comprising the following inweight percent: derivatized phenol at 65-75% tert-butyl-catechol at22-35% phenothiazine at 0-0.75%.
 15. The composition of claim 14,comprising the following in weight percent: derivatized phenol at about66.5% tert-butyl-catechol at about 33% phenothiazine at about 0.5%. 16.A polyurethane foam, comprising a scorch inhibitor composition accordingto any of claims 1-15.